I've configured a brand new system. I installed win 10 on my boot drive (Samsung 950 pro nmve). The system is running in RAID mode. Then I succesfully created a Raid 5 set of my 3 classic HDDs. No problem. Then I reboot and IRST warns me, that there is a status problem. The Raid Type is unknown and the Volume inkompatible. But except for this warning everything seems to run fine. I deleted the Raid set and rebuild it -> same warning after reboot. I tried Raid 1 -> same warning after reboot. As long as I don't reboot there is no warning. What is going on here?

I can't CTRL+I. The Raid control is integrated in my bios. I took 3 pictures from the windows control.

Here the RAID is working as expected:

And here with wrning after reboot:

In the meantime I tested some bios settings and the result is, that I have to disable the Windows Fast Boot option. If I do that, the warning vanishs and I have a stable system without RAID warnings for 2 days.